Lens driving device

ABSTRACT

A lens driving device is provided, including a frame, a lens holder, a spring sheet, and at least one damping element. The lens holder is movably disposed in the frame. The spring sheet has an outer periphery portion combined with the frame, an inner periphery portion combined with the lens holder, and an arm portion connected between the outer periphery portion and the inner periphery portion. The damping element is connected between the arm portion of the spring sheet and at least one of the frame and the lens holder.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/164,357, filed on Oct. 18, 2018, which is a continuation of application Ser. No. 15/181,145, filed on Jun. 13, 2016, which claims the priority of Taiwan Patent Application No. 104140047, filed on Dec. 1, 2015, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a lens driving device, and in particular to a lens driving device which requires less focusing time.

Description of the Related Art

Many mobile devices such as mobile phones are equipped with digital cameras as a basic requirement nowadays, and this is only possible thanks to the miniaturization of lens driving devices. In order to provide automatic focusing or zooming, a commonly used miniature lens driving device is a Voice Coil Motor (VCM), which carries a lens and can move the lens back and forth along an image-capturing optical axis by means of a coil, a magnet, and a spring sheet.

Generally, when a lens (of VCM) is moved to a fixed position to bring the subject into focus, it may shake for a period, and then is slowly reaches a steady state. This time required (for the lens) to move to the stop from being at rest is called the Dynamic Response Time, which affects the length of the focusing time of the lens driving device (The longer the Dynamic Response Time, the longer the focusing time. This adversely affects the effectiveness of the lens driving device). Therefore, how to shorten the Dynamic Response Time to reduce the focusing time of the lens driving device deserves careful consideration.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide a lens driving device which can reduce the shake generated by focusing the lens, so that the Dynamic Response Time and hence the focusing time can be shortened.

An embodiment of the invention provides a lens driving device, including a frame, a lens holder, a spring sheet, and at least one damping element. The lens holder is movably disposed in the frame. The spring sheet has an outer periphery portion, an inner periphery portion, and at least one arm portion. The outer periphery portion is combined with the frame, the inner periphery portion is combined with the lens holder, and the arm portion is connected between the outer periphery portion and the inner periphery portion. The damping element is connected between the arm portion of the spring sheet and at least one of the frame and lens holder.

In some embodiments, the arm portion of the spring sheet forms at least one protrusion that extends toward the frame, and the frame forms at least one recess corresponding to the protrusion, wherein the damping element is connected between the protrusion and the recess.

In some embodiments, the arm portion of the spring sheet forms at least one protrusion that extends toward the lens holder, and the lens holder forms at least one recess corresponding to the protrusion, wherein the damping element is connected between the protrusion and the recess.

In some embodiments, the frame forms at least one connected portion that protrudes from an inner side thereof, and the damping element is connected between the arm portion of the spring sheet and the connected portion.

In some embodiments, the inner periphery portion of the spring sheet forms at least one opening to which a part of a connected surface of the lens holder is exposed, and the damping element is connected between the arm portion of the spring sheet, the opening, and the exposed part of the connected surface of the lens holder.

In some embodiments, the damping element is connected to the arm portion of the spring sheet in a winding manner.

In some embodiments, the damping element is a soft gel.

In some embodiments, the damping element, the frame, and the lens holder comprise the same resin material.

In some embodiments, the frame and the spring sheet are respectively a top casing and an upper spring sheet of the lens driving device.

In some embodiments, the frame and the spring sheet are respectively a bottom base and a lower spring sheet of the lens driving device.

In order to illustrate the purposes, features, and advantages of the invention, the preferred embodiments and drawings of the invention are shown in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is an exploded view of a lens driving device in accordance with an embodiment of the invention;

FIG. 2 is a schematic view of the lens driving device in FIG. 1 after assembly;

FIG. 3A is a schematic plane view illustrating the configuration of the spring sheet, damping elements, and frame of a lens driving device in accordance with an embodiment of the invention, and FIG. 3B is an enlarged perspective view of part A of FIG. 3A;

FIG. 4 is a schematic cross-sectional view illustrating the connection between the spring sheet and damping element in accordance with another embodiment of the invention;

FIG. 5A is a schematic plane view illustrating the configuration of the spring sheet, damping elements, and frame of a lens driving device in accordance with another embodiment of the invention, and FIG. 5B is an enlarged perspective view of part B of FIG. 5A;

FIG. 6A is a schematic plane view illustrating the configuration of the spring sheet, damping elements, and lens holder of a lens driving device in accordance with another embodiment of the invention, and FIG. 6B is an enlarged perspective view of part C of FIG. 6A;

FIG. 7A is a schematic plane view illustrating the configuration of the spring sheet, damping elements, and lens holder of a lens driving device in accordance with another embodiment of the invention, and FIG. 7B is an enlarged perspective view of part D of FIG. 7A;

FIG. 8A is a schematic plane view illustrating the configuration of the spring sheet, damping elements, and frame of a lens driving device in accordance with another embodiment of the invention, and FIG. 8B is an enlarged perspective view of part E of FIG. 8A; and

FIG. 9A is a schematic plane view illustrating the configuration of the spring sheet, damping elements, and lens holder of a lens driving device in accordance with another embodiment of the invention, and FIG. 9B is an enlarged perspective view of part F of FIG. 9A.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description is given in the following embodiments with reference to the accompanying drawings.

In the following detailed description, the orientations of “on”, “above”, “under”, and “below” are used for representing the relationship between the relative positions of each element as illustrated in the drawings, and are not meant to limit the invention.

In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Various features may be arbitrarily drawn in different scales for the sake of simplicity and clarity. Furthermore, some elements not shown or described in the embodiments have the forms known by persons skilled in the field of the invention.

Please refer to FIG. 1 and FIG. 2, wherein FIG. 1 is an exploded view of a lens driving device 1 in accordance with an embodiment of the invention, and FIG. 2 is a schematic view of the lens driving device 1 after assembly. The lens driving device 1 may be a Voice Coil Motor (VCM), which defines three axial directions that are perpendicular to each other, namely an X-axis direction, a Y-axis direction, and a Z-axis direction, and includes a lens (not shown) therein, wherein the lens defines an image-capturing optical axis O which is substantially parallel to the Z-axis.

As shown in FIG. 1 and FIG. 2, the lens driving device 1 includes a top casing 10, a bottom base 20, a lens holder 30, a coil 40, a plurality of (e.g. four) magnets 50, an upper spring sheet 60, and a lower spring sheet 70.

In this embodiment, the top casing 10 is a hollow structure and can be combined with the bottom base 20 to form a receiving space, for receiving and protecting other parts of the lens driving device 1 as described above. Also, the top casing 10 has an opening 12 through which the lens (not shown) in the lens driving device 1 can capture light from the outside. The lens holder 30 is a hollow ring structure having a substantially octangular periphery and has a through hole 32, wherein the through hole 32 forms a thread structure 322 corresponding to another thread structure on the lens, such that the lens can be locked in the through hole 32. The coil 40 is wound around the periphery of the lens holder 30. The magnets 50 may be permanent magnets and are fixed at the four respective corners of the bottom base 20 and correspond to the coil 40. By varying the current input into the coil 40, different magnetic fields are generated between the coil 40 and the magnets 50 to drive the lens holder 30 and the lens therein back and forth along the image-capturing optical axis O, so that focusing or zooming is carried out

It should be realized that the lens holder 30 is movably disposed in the receiving space formed by the top casing 10 and the bottom base 20 (the top casing 10 and the bottom base 20 form the frame of the lens driving device 1), and is elastically clamped by the movable inner periphery portions of the upper spring sheet 60 and the lower spring sheet 70. Accordingly, the upper and lower spring sheets 60 and 70 can limit the range in which the lens holder 30 can be moved and provide the buffer capacity for the displacement of the lens holder 30 along the X-axis, the Y-axis, and the Z-axis.

However, the above design (i.e. the lens holder 30 being clamped by the upper and lower spring sheets 60 and 70 which are flexible and thin sheet structure) also results in vibration/shake of the lens holder 30 and the lens therein when it is moved to a fixed position to bring the subject into focus, so that the Dynamic Response Time is extended. Therefore, the following further describes damping elements are used in various embodiments (with reference to FIGS. 3 to 9) of the invention so as to absorb and inhibit the shake generated by focusing the lens, thereby shortening the Dynamic Response Time and the focusing time and further improving the effectiveness of the lens driving device 1.

Please refer to FIG. 3A and FIG. 3B, wherein FIG. 3A is a schematic plane view illustrating the configuration of the spring sheet 60, damping elements 80, and frame 10 of a lens driving device in accordance with an embodiment of the invention, and FIG. 3B is an enlarged perspective view of part A of FIG. 3A. It should be realized that the upper spring sheet 60 and the top casing 10 of the lens driving device 1 are used as examples for illustration in this embodiment, but the upper spring sheet 60 and the top casing 10 may also be replaced by the lower spring sheet 70 and the bottom base 20 of the lens driving device 1 (FIG. 1).

As shown in FIG. 3A and FIG. 3B, the spring sheet 60 includes an outer periphery portion 62 having a substantially rectangular shape, an inner periphery portion 64 having a substantially annular shape, and a plurality of (e.g. four) elongated arm portions 66 connected between the outer periphery portion 62 and the inner periphery portion 64. The outer periphery portion 62 is configured to be combined with the four corners of the top casing 10 (the frame) by, for example, adhesive. The inner periphery portion 64 is configured to be combined with the lens holder 30 by, for example, adhesive. The four arm portions 66 extend between the outer periphery portion 62 and the inner periphery portion 64 and are symmetrical to each other with equal intervals, so as to increase the buffer capacity for the displacement of the lens holder 30 along the X-axis, the Y-axis, and the Z-axis.

Moreover, a plurality of (e.g. four) damping elements 80 can be disposed between the arm portions 66 of the spring sheet 60 and (the four corners of) the adjacent frame 10, wherein the damping elements 80 are coupled to the arm portions 66 and to the frame 10 (FIG. 3B), so that the damping elements 80 can absorb and inhibit the shake generated by the arm portions 66 of the spring sheet 60 when the lens is moved to a fixed position to bring the subject into focus. Therefore, the Dynamic Response Time and the focusing time are effectively shortened.

The damping elements 80 may be soft gel or any other applicable damping material. Also, the frame 10, preferably, may comprise resin material, so that a better bonding strength can be achieved between the damping elements 80 and the frame 10, thereby preventing the damping elements 80 from easily separating from the frame 10.

FIG. 4 is a schematic cross-sectional view illustrating the connection between the spring sheet 60 and damping element 80 in accordance with another embodiment of the invention. As shown in FIG. 4, the damping element 80 can also be connected to the arm portion 66 of the spring sheet 60 in a winding manner. Thus, the bonding strength between the damping elements 80 and the metal spring sheet 60 can also be improved, thereby preventing the damping elements 80 from easily separating from the spring sheet 60.

Please refer to FIG. 5A and FIG. 5B, wherein FIG. 5A is a schematic plane view illustrating the configuration of the spring sheet 60, damping elements 80, and frame 10 of a lens driving device in accordance with another embodiment of the invention, and FIG. 5B is an enlarged perspective view of part B of FIG. 5A. Note that this embodiment (FIGS. 5A and 5B) differs from the embodiment of FIGS. 3A and 3B in that the arm portions 66 of the spring sheet 60 further form a plurality of (e.g. four) protrusions 66A that extend toward the frame 10 and correspond to the four corners of the frame 10. Also, the frame 10 further forms a plurality of recesses 14 (FIG. 5B) corresponding to the protrusions 66A. Accordingly, the damping elements 80 can be connected between the protrusions 66A of the arm portions 66 and the recesses 14 of the frame 10 (in this embodiment, the damping elements 80 are coupled to the protrusions 66A and to the recesses 14, and parts of the damping elements 80 will flow into the gaps between the lower surfaces of the protrusions 66A and the recesses 14), so that the damping elements 80 can absorb and inhibit the shake generated by the arm portions 66 of the spring sheet 60 when the lens is moved to a fixed position to bring the subject into focus, thereby effectively shortening the Dynamic Response Time and the focusing time.

Moreover, the recesses 14 of this embodiment each are designed to have a triangular shape (but the invention is not limited thereto), and the damping element 80 correspondingly covers the entire triangular recess 14. Thus, the bonding strength between the damping elements 80 and the frame 10 can be increased, and the bonding strength between the protrusions 66A of the arm portions 66 and the frame 10 can also be increased. Furthermore, with the design of the recesses 14, the damping elements 80 can be accurately adhered to and positioned in the desired positions, and the use amount of damping elements 80 is reduced.

Please refer to FIG. 6A and FIG. 6B, wherein FIG. 6A is a schematic plane view illustrating the configuration of the spring sheet 60, damping elements 80, and lens holder 30 of a lens driving device in accordance with another embodiment of the invention, and FIG. 6B is an enlarged perspective view of part C of FIG. 6A. Note that this embodiment (FIGS. 6A and 6B) differs from the embodiment of FIGS. 3A and 3B in that the plurality of damping elements 80 are disposed between the arm portions 66 of the spring sheet 60 and the lens holder 30, wherein the damping elements 80 are coupled to the arm portions 66 and to the lens holder 30 (FIG. 6B), so that the damping elements 80 can absorb and inhibit the shake generated by the arm portions 66 of the spring sheet 60 when the lens is moved to a fixed position to bring the subject into focus, thereby effectively shortening the Dynamic Response Time and the focusing time.

In this embodiment, the damping elements 80 may be soft gel or any other applicable damping material. Also, the lens holder 30, preferably, may comprise resin material, so that a better bonding strength can be achieved between the damping elements 80 and the lens holder 30, thereby preventing the damping elements 80 from easily separating from the lens holder 30. In some embodiments, the damping element 80 can also be connected to the arm portion 66 of the spring sheet 60 in a winding manner. Thus, the bonding strength between the damping elements 80 and the metal spring sheet 60 can also be improved, thereby preventing the damping elements 80 from easily separating from the spring sheet 60.

Please refer to FIG. 7A and FIG. 7B, wherein FIG. 7A is a schematic plane view illustrating the configuration of the spring sheet 60, damping elements 80, and lens holder 30 of a lens driving device in accordance with another embodiment of the invention, and FIG. 7B is an enlarged perspective view of part D of FIG. 7A. Note that this embodiment (FIGS. 7A and 7B) differs from the embodiment of FIGS. 6A and 6B in that the arm portions 66 of the spring sheet 60 further form a plurality of (e.g. four) protrusions 66B that extend toward the lens holder 30, and the lens holder 30 further forms a plurality of recesses 34 (FIG. 7B) corresponding to the protrusions 66B. Accordingly, the damping elements 80 can be connected between the protrusions 66B of the arm portions 66 and the recesses 34 of the lens holder 30 (in this embodiment, the damping elements 80 are coupled to the protrusions 66B and to the recesses 34, and parts of the damping elements 80 will flow into the gaps between the lower surfaces of the protrusions 66B and the recesses 34), so that the damping elements 80 can absorb and inhibit the shake generated by the arm portions 66 of the spring sheet 60 when the lens is moved to a fixed position to bring the subject into focus, thereby effectively shortening the Dynamic Response Time and the focusing time.

Moreover, the recesses 34 of this embodiment each are designed to have a semicircular shape (but the invention is not limited thereto), and the damping element 80 correspondingly covers the entire semicircular recess 34. Thus, the bonding strength between the damping elements 80 and the lens holder 30 can be increased, and the bonding strength between the protrusions 66B of the arm portions 66 and the lens holder 30 can also be increased. Furthermore, with the design of the recesses 34, the damping elements 80 can be accurately adhered to and positioned in the desired positions and the use amount of damping elements 80 is reduced.

Please refer to FIG. 8A and FIG. 8B, wherein FIG. 8A is a schematic plane view illustrating the configuration of the spring sheet 70, damping elements 80, and frame 20 of a lens driving device in accordance with another embodiment of the invention, and FIG. 8B is an enlarged perspective view of part E of FIG. 8A. It should be realized that the lower spring sheet 70 and the bottom base 20 of the lens driving device 1 are used as examples for illustration in this embodiment, but the lower spring sheet 70 and the bottom base 20 may also be replaced by the upper spring sheet 60 and the top casing 10 of the lens driving device 1 (FIG. 1).

As shown in FIG. 8A and FIG. 8B, the spring sheet 70 also includes an outer periphery portion 72 configured to be combined with the bottom base 20 (the frame), an inner periphery portion 74 configured to be combined with the lens holder 30 (not shown), and a plurality of (e.g. four) elongated arm portions 76 connected between the outer periphery portion 72 and the inner periphery portion 74.

Moreover, the four sidewalls of the bottom base 20 further respectively form a connected portion 22 (FIG. 8B) that protrudes from the inner side thereof, and the corresponding arm portion 76 of the spring sheet 70 can be disposed on a side (e.g. the upper side) of the connected portion 22. Also, a plurality of damping elements 80 can be disposed between the arm portions 76 of the spring sheet 70 and the adjacent connected portions 22. More specifically, the damping elements 80 are adhered to the connected portions 22 and the inner sidewalls of the bottom base 20 and are connected to the arm portions 76 of the spring sheet 70 in a winding manner (it should be noted that the damping elements 80 each are at least connected to two opposite surfaces and another surface between the two surfaces of the corresponding arm portion 76), so that the damping elements 80 can absorb and inhibit the shake generated by the arm portions 76 of the spring sheet 70 when the lens is moved to a fixed position to bring the subject into focus, thereby effectively shortening the Dynamic Response Time and the focusing time. Furthermore, with the design of connected portions 22, the damping elements 80 can be accurately adhered to and positioned in the desired positions.

In this embodiment, the damping elements 80 may be soft gel or any other applicable damping material. Also, the bottom base 20 (the frame), preferably, may comprise resin material, so that a better bonding strength can be achieved between the damping elements 80 and the bottom base 20, thereby preventing the damping elements 80 from easily separating from the bottom base 20.

Please refer to FIG. 9A and FIG. 9B, wherein FIG. 9A is a schematic plane view illustrating the configuration of the spring sheet 70, damping elements 80, and lens holder 30 of a lens driving device in accordance with another embodiment of the invention, and FIG. 9B is an enlarged perspective view of part F of FIG. 9A. It should be realized that the lower spring sheet 70 of the lens driving device 1 is used as an example for illustration in this embodiment, but the lower spring sheet 70 may also be replaced by the upper spring sheet 60 (FIG. 1).

In this embodiment, the spring sheet 70 further forms a plurality of (e.g. four) openings 74A (FIG. 9B) on the inner periphery portion 74 for exposing parts of the connected surface of the lens holder 30. Moreover, the damping elements 80 are connected between the arm portions 76 of the spring sheet 70, the openings 74A and the exposed parts of the connected surface of the lens holder 30. Since the damping elements 80 are coupled to the arm portions 76 and to the lens holder 30, the damping elements 80 can absorb and inhibit the shake generated by the arm portions 76 of the spring sheet 70 when the lens is moved to a fixed position to bring the subject into focus, thereby effectively shortening the Dynamic Response Time and the focusing time.

With the design of openings 74A, the damping elements 80 may flow into the openings 74A and then are connected between the arm portions 76 of the spring sheet 70, the openings 74A, and the exposed parts of the connected surface of the lens holder 30. Thus, the damping elements 80 can be accurately adhered to and positioned in the desired positions and the bonding strength between the damping elements 80 and the lens holder 30 can also be improved further. In this embodiment, the damping elements 80 may be soft gel or any other applicable damping material. Also, the lens holder 30, preferably, may comprise resin material, so that a better bonding strength can be achieved between the damping element 80 and the lens holder 30, thereby preventing the damping elements 80 from easily separating from the lens holder 30. In some embodiments, the damping elements 80 may also be connected to the arm portions 76 of the spring sheet 70 in a winding manner, so that the boding strength between the damping elements 80 and the spring sheet 70 comprising metal material can also be improved further, thus preventing the damping elements 80 from easily separating from the spring sheet 70.

Although the lens driving device 1 of the aforementioned embodiments is used as a Voice Coil Motor (VCM), the invention is not limited thereto. The lens driving device provided in some embodiments of the invention may also be used in a camera module with Optical Image Stabilization (OIS) technology since it can drive the camera along the X-axis and the Y-axis.

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A lens driving device, comprising: a frame; a lens holder, movably connected to the frame, for holding a lens with an optical axis; a spring sheet, disposed at the frame, wherein the spring sheet comprises: an outer periphery portion, fixedly connected to the frame; and a protrusion, extending toward the lens holder and comprising a placement portion and an extending portion, wherein the placement portion is connected to the outer periphery portion via the extending portion; a damping element, disposed at the placement portion; wherein when viewing from the optical axis, the damping element and the lens holder are partially overlapped; wherein the lens holder further comprises a recess corresponding to the protrusion, and when viewing in a direction that is perpendicular to the optical axis, the placement portion and the recess are at least partially overlapped.
 2. The lens driving device as claimed in claim 1, wherein when viewing from the optical axis, the protrusion and the lens holder are partially overlapped.
 3. The lens driving device as claimed in claim 1, wherein the damping element covers the recess.
 4. The lens driving device as claimed in claim 1, wherein the spring sheet has a plate structure, extending along a direction perpendicular to the optical axis.
 5. The lens driving device as claimed in claim 1, wherein when viewing from the optical axis, the protrusion and the recess are partially overlapped.
 6. The lens driving device as claimed in claim 5, wherein a part of the damping element is located in the recess.
 7. The lens driving device as claimed in claim 1, wherein the damping element is connected to the protrusion and the recess.
 8. The lens driving device as claimed in claim 7, wherein a part of the damping element is located between the protrusion and the recess.
 9. The lens driving device as claimed in claim 1, further comprising a driving assembly, driving the lens holder to move relative to the frame.
 10. The lens driving device as claimed in claim 9, wherein the lens holder is driven by the driving assembly to move along the optical axis relative to the frame.
 11. The lens driving device as claimed in claim 1, further comprising a gap between the protrusion and the lens holder, wherein the protrusion and the lens holder are not in direct contact.
 12. The lens driving device as claimed in claim 11, wherein a part of the damping element is disposed in the gap.
 13. The lens driving device as claimed in claim 1, wherein the protrusion has a surface, corresponding to a surface of the recess, wherein the surface of the protrusion and the surface of the recess are both parallel to the optical axis.
 14. The lens driving device as claimed in claim 13, wherein a part of the damping element is disposed between the surface of the protrusion and the surface of the recess and is connected to the surface of the protrusion and the surface of the recess.
 15. The lens driving device as claimed in claim 1, further comprising a plurality of damping elements, wherein the spring sheet further comprises a plurality of protrusions, and the lens holder further comprises a plurality of recesses, wherein an amount of the plurality of damping elements, an amount of the plurality of protrusions, and an amount of the plurality of recesses are the same, wherein the plurality of damping elements, the plurality of protrusions, and the plurality of recesses respectively correspond to one another.
 16. The lens driving device as claimed in claim 15, wherein the plurality of damping elements are disposed around the optical axis.
 17. The lens driving device as claimed in claim 16, wherein the plurality of damping elements extends toward the optical axis. 